How do u convert 3.5mol to umol

"umol" stands for micromole. You can convert mole into micromole by multiplying a certain factor. For this case, 1 mol is known to be equal yo 1x10^6 umol. This is the conversion factor that will be multiplied to 3.5.

3.5 mol (1x10^6 umol / 1 mol) = 3.5 x10^6 umol